One particular tube upgrade elim my speaker hum

Have been trying for a year to reduce the hum heard when up close to the speaker with volume at 50%. I have Level 1 modded Shanling Tube monoblocks, TAD 150 preamp, and Level 1 modded Maverick SACD player.Speakers are Meadowlark Blue Heron 2's. Switched from Signal Cable interconnects to Silent Audio to Audio Metallurgy GA-0's. Speaker cables went from Signal Cable, to anti cables, to MAS Silver Hybrid. Still had hum at the speaker. Replaced 12ax7s in preamp with rca blackplates, then the el34's powering the amp with Amperex Bugle Boy. What made the difference was putting in Tung Sol 6SN7 tall bottles in the amps. Dead, dead quiet! Highs are better then before. Tube rolling pays off ($500 later!) Includes yet to be installed RCA red base 6SL7's.
Seems there are a million variables, feels good to nail something down finally!